-- Robert Straley, 66, of Clearwater, who co-authored a book about his experience at the Dozier School for Boys

Sen. Bill Nelson on Wednesday called on the Department of Justice to assist a team of anthropologists and archaeologists from the University of South Florida that has been investigating the deaths of nearly 100 children at Florida's oldest reform school, the now-shuttered Dozier School for Boys outside the Panhandle town of Marianna.

Nelson (D-Fla.) sent a letter to U.S. Attorney General Eric Holder after the USF team released a report on Monday saying it had found 50 grave shafts on school property, 19 more than Florida Department of Law Enforcement investigators found during an investigation in 2009.

"The reform school may yield some ugly reminders about our past, but we absolutely must get to the bottom of this," Nelson said.